Solid freeform fabrication (SFF) is a process whereby three-dimensional objects, for example, prototype parts, models, working tools, production parts, molds, and other articles are manufactured. Computer aided design (CAD) is commonly used to automate the design process. Using a suitable computer, an operator may design a three-dimensional article and then create that object by the use of a positionable ejection head that selectively emits a desired material. While many methods have been developed to manufacture SFF objects according to the above principles, two methods have traditionally been preferred for manufacturing SFF objects: powder/binder interaction to create a solid object, and the use of jetted curable photopolymers to create a solid object.
Powder/binder interaction forming methods include the selective deposition of a binder onto powder constituents. Once deposited, the powder constituents react with the binder to create a solid object. In many cases powder/binder interaction boils down to swelling of a polymer component of the powder in a solvent present in the binder. In order to incorporate the traditional powder and binder interaction method, both the binder and the powder must be finely tuned to chemically react when combined. This limits the types of powders and binders that may be used. Additionally, this method tends to result in porous final structures. Moreover, low dimensional accuracy may result from this method due to swelling of the powder constituents during the powder/binder interaction.
Jetted photopolymer methods include the selective deposition of both build and support material from a dispenser onto a substrate where the two materials subsequently solidify. While dimensional accuracy is improved by this method, jetted photopolymer methods are slower than methods that apply material in a bulk process. Additionally, the costs of jetted photopolymer machines are high because they require both a material dispenser and a material reservoir for each material dispensed. In these jetted photopolymer technologies, both the build and the support material must be jetted through the material dispensers.